Hybrid External Fixation For Tibial Plateau Fractures: A Biomechanics Study

Objective: For tibial plateau fractures , especially thosecaused by a higher-energy mechanism of injury , always mergewith severe soft tissue injury , these fractures have beenassociated with high incidence of severe complications whentreated with traditional techniques such as dual buttress plates .The new technical of hybrid external fixation have someadvantages such as little injury and few severe complications .But in the clinical course , which kind of frame configurationwas coincidental with biomechanical principle and which onehas similar stability with dual buttress plates is worth studying .In this study , we compared three different hybrid externalfixation frame configuration to dual buttress plates to find thekey points about them in the clinical course . Methods: Four embalmed lower limbs were harvested forthis study . At first knee disarticulation was performed in allsamples , then the surrounding soft tissue of the tibial plateauwere rejected , four simulated complex proximal plateaufractures(Schatzker Ⅵ ) were developed in the self-madetemplate according to the left or right , the simulated fracturewas then stabilized using one of the following hybrid wireconfigurations or plating : two counteropposed wires(30°) , 4英 文 摘 要two counteropposed wires (70°) , three wires , two buttressplates . First the simulated fracture model was fixed in theself-made fixturn , the level of the joint surface should be kept .The self-made simulated femoral condyle was connected to thedrive axis of the biomechanical test machine (Model :css-44020,Changchun,China). Then the fracture model was puton the test table , two axis of simulated femoral condyle andfracture model were kept on one line . Each model was thencyclically loaded to 300N at standard loading rates (2mm/min)in the biomechanical test machine . The distance and the heightof the medial and lateral simulated femoral condyle were adjustto a suitable degree to ensure the simulated femoral condylescould press on the articular surface of tibia at the same time .The speed of the drive axis of the biomechanical test machinewas designed at 2mm/min , until 300N, and keeping 10s, thedata of displacement of the medial condyle , lateral condyle anddrive axis were recorded respectively . Then the drive axis wasraised 10cm above the level of the articular surface of tibia .After the previous course has been repeated four times , thesecond fixation was used and tested . When the tests of othertwo fixation were finished , the other sample' tests wereoperated one by one . With 20 mechanical tests each fixationtechnique , there was 80 data for every displacement , 240 datapoints were sufficient to achieve statistical significance . Results: All data was separated three groups : medialcondyle displacement , lateral condyle displacement and 5英 文 摘 要actuator displacement . The outcome of 30 ° -two-wireexternal fixation , 70°-two-wire external fixation , three-wiresexternal fixation and dual buttress plates internal fixation wasconsisted in each data group . Statistical analysis was done forall data of medial condyle displacement , lateral condyledisplacement and actuator displacement . By the method ofSkewness/Kurtosis tests for normality , not all of the datumwere normally distributed . Through Bartlett's test for egualvariances , the variances of the three groups weren't egual . Sothese datum were comparable through Kruskal-Wallis testsrespectively . The statistic analysis of medial condyle displacementshowed that there was significant difference among 30 °-two-wire external fixation , 70°-two-wire external fixation ,three-wires external fixation and dual buttress plates internalfixation (P<0.05) . The statistic analysis of lateral condyledisplacement and drive axis displacement showed the sameresult (P<0.05) . Then four fixation met...